Trade deal with EU could take more than a year - Key

It'll be at least another year before formal negotiations begin on a free trade deal between New Zealand and the European Union, Prime Minister John Key says.

Mr Key has been in Berlin where he's met with German Chancellor Angela Merkel.

The EU's recent commitment to start talks on a free trade deal was among the topics up for discussion.

But Mr Key says there's still some way to go before those formal negotiations get off the ground.

"The process now is that the European Commission will go through the mandating process - that's likely to take all of 2016 and probably most of 2017 to get through the 28 member states, but we're very hopeful for completion of the free trade agreement with Europe," he told a joint press conference with Ms Merkel.

Mr Key met European Council President Donald Tusk and European Commission President Jean-Claude Juncker in late October, when it was agreed New Zealand and the EU would start talks on a deal.

In 2014 the EU was New Zealand's third largest trading partner, after Australia and China, with two-way trade totalling over $19 billion.